feat(turbopack): externalType support script (#80768)
This pr introduce a new external type: `Script`, which has the same
behaviour as webpack's
https://webpack.js.org/configuration/externals/#externalstypescript
And i also refer to the webpack's implement, this external type accept a
request like: `root@script_url` which same as webpack:
In the utoo, we use it as follows:
https://github.com/umijs/mako/blob/next/crates/pack-core/src/shared/resolve/externals_plugin.rs#L202-L208
It will generate runtime code to load the external package from the
`script_url`
